The newer tennis shoes these days have a breathable upper, but they are putting rubber on the bottom of the insole for better cushioning. Because of this, I cannot wear any of these shoes even though they are almost all netting on the top because the rubber makes my feet sweat.
After trying many different shoes and insoles, I tried the Spenco Polysorb Flow Cool Insoles and they have been a life-saver. They work wonders in dissipating the heat from the bottom of my feet.
Brian